A buck converter comprising a controller arranged to monitor an output voltage of the converter, the controller comprising: a comparator arranged to compare an output voltage at an output of the buck converter with a reference voltage, and a modification circuit within the comparator or connected to a modification signal input of the comparator and arranged to produce a correction signal to modify the operation of the comparator; and an output.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A buck converter that produces an output voltage and that includes: an inductor; a controller arranged to monitor the output voltage; a switching arrangement responsive to the output of the controller for selectively connecting a first terminal of the inductor to a first voltage or to a second voltage; and a storage element connected to a second terminal of the inductor; wherein the controller comprises: a comparator arranged to compare a feedback signal representative of the output voltage with a reference voltage, and a modification circuit within the comparator or connected to a modification signal input of the comparator and arranged to produce a correction signal to modify the operation of the comparator; wherein the modification circuit receives a modification circuit input signal representing the first voltage or the second voltage selectively connected to the first terminal of the inductor; wherein the modification circuit includes an integrator coupled to receive a modification circuit input signal representing the voltage at the first terminal of the inductor, to integrate the modification circuit input signal and to produce an integrator output signal; wherein the modification circuit includes a voltage controlled current flow control device; wherein the integrator is coupled to supply at least a portion of the integrator output signal to control the voltage controlled current flow control device to produce the correction signal to modify the operation of the comparator; and wherein the modification circuit includes a DC block coupled between the integrator and the voltage controlled current flow device to block a DC component of the integrator output signal and to pass an AC component of the integrator output signal.
2. The buck converter as claimed in claim 1 , in which the modification circuit further includes a scaling circuit for applying a scaling factor to the modification circuit input signal or to an output of the integrator.
3. The buck converter as claimed in claim 1 , in which the modification circuit includes a ripple extraction circuit or component, so as to extract a time varying signal from a substantially invariant background.
4. The buck converter as claimed in claim 1 , in which the comparator has a differential input stage, comprising first and second field effect transistors each exhibiting a first transconductance, and the modification circuit modifies a current flowing through at least one of the first and second transistors.
5. The buck converter as claimed in claim 1 , further including a frequency controller arranged to modify a switching frequency of the switching arrangement.
6. The buck converter as claimed in claim 1 , in which the comparator exhibits hysteresis.
7. The buck converter as claimed in claim 1 , in which the modification circuit emulates the current flowing in the inductor.
8. The buck converter as claimed in claim 7 , in which the modification circuit integrates an input signal so as to emulate the current flowing in the inductor.
9. The buck converter as claimed in claim 8 , in which the modification circuit scales the emulated current or the integral thereof.
10. The buck converter as claimed in claim 9 , in which the current flowing in the inductor is emulated by at least one of a current source and a current sink arranged to charge and discharge a capacitor.
11. A buck converter comprising a controller arranged to monitor an output voltage of the converter, the controller comprising: a comparator arranged to compare a feedback signal representative of an output voltage at an output of the buck converter with a reference voltage; a modification circuit within the comparator or connected to a modification signal input of the comparator and arranged to produce a correction signal to modify the operation of the comparator; an output; wherein the comparator includes a differential input stage, comprising first and second field effect transistors each exhibiting a first transconductance, and the modification circuit modifies a current flowing through at least one of the first and second transistors; a current source or current sink in series with a third field effect transistor having a transconductance, wherein the third field effect transistor has its gate arranged to receive an integrated version of the modification circuit input signal; and a node between the current source or current sink and the third field effect transistor is connected to a drain of one of the first and second field effect transistors.
12. A buck converter comprising a controller arranged to monitor an output voltage of the converter, the controller comprising: a comparator arranged to compare a feedback signal representative of the output voltage with a reference voltage, and a modification circuit within the comparator or connected to a modification signal input of the comparator and arranged to produce a correction signal to modify the operation of the comparator; an output; a frequency controller arranged to modify a switching frequency of the switching arrangement; and a frequency or phase comparator arranged to control current to be selectively added to or removed from a output of the comparator where the comparator outputs a current as a function of a voltage difference between the output voltage and the reference voltage.
13. The buck converter as claimed in claim 12 further comprising a controllable current flow device to deliver current to a summing node of the comparator.
14. The buck converter as claimed in claim 12 , further comprising a controllable current flow device to remove current from a summing node of the comparator.
15. The buck converter as claimed in claim 12 , in which the comparator comprises a differential pair, and a current control device is connected to each arm of the differential pair and enabled or disabled in accordance with a switching signal generated by the differential pair.
16. A buck converter that produces an output voltage and that includes: an inductor; a controller arranged to monitor an output voltage of the converter; a switching arrangement responsive to the output of the controller for selectively connecting a first terminal of the inductor to a first voltage or to a second voltage; and a storage element connected to a second terminal of the inductor; wherein the controller comprises: a comparator arranged to compare a feedback signal representative of an output voltage at an output of the buck converter with a reference voltage, and a modification circuit within the comparator or connected to a modification signal input of the comparator and arranged to produce a correction signal to modify the operation of the comparator; an output; a frequency controller arranged to modify a switching frequency of the switching arrangement; wherein the comparator has a differential input stage, comprising first and second field effect transistors each exhibiting a first transconductance, and the modification circuit modifies a current flowing through at least one of the first and second transistors; wherein the modification circuit comprises a differential transconductance amplifier having a first current output connected to a first summing node of the comparator differential input stage, and a second current output connected to a second summing node of the comparator differential input stage, and a first input of the differential transconductance amplifier receives an integrated version of the voltage supplied to the voltage at the first terminal of the inductor or an emulated version thereof, and the second input of the differential amplifier receives a hysteresis control signal.
17. The buck converter as claimed in claim 16 , in which the signals supplied to the first and second inputs have a bias voltage superimposed thereon.
18. The buck converter as claimed in claim 16 , in which a DC component of the integrated version of the voltage supplied to the first terminal of the inductor is removed.
19. The buck converter as claimed in claim 16 , in which the hysteresis control signal is an alternating signal.
20. The buck converter as claimed in claim 16 , in which the hysteresis signal control is a square wave.
21. The buck converter as claimed in claim 16 , in which a magnitude of the hysteresis control signal is used to control a difference between switching thresholds in the controller.
22. The buck converter as claimed in claim 16 , comprising a further comparator stage having a first input connected to the first summing node of the comparator differential input stage and a second input connected to the second summing node of the comparator differential input stage.
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April 11, 2012
March 3, 2015
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